1. Technical Field
This invention relates to a hybrid vehicle, and more specifically, to a hybrid vehicle that is equipped with an internal combustion engine, an electrical storage device, and an electric motor that generates a running driving force upon being supplied with an electric power from the electrical storage device.
2. Background
Japanese Patent Application Publication No. 2013-252853 (JP 2013-252853 A) discloses a hybrid vehicle having a charge depleting (CD) mode and a charge sustaining (CS) mode. The CD mode is a mode in which the state of charge (the SOC) of an electrical storage device is actively consumed by mainly carrying out EV running while permitting HV running. The CS mode is a mode in which the SOC is controlled to a predetermined range by appropriately making a changeover between HV running and EV running. Incidentally, during EV running, the hybrid vehicle runs using only a motor-generator with an engine stopped. During HV running, the hybrid vehicle runs with the engine in operation. Then, it is described that the threshold of a power at which the engine starts is made larger in the CD mode than in the CS mode (see Japanese Patent Application Publication No. 2013-252853 (JP 2013-252853 A)).
With the hybrid vehicle described in the aforementioned Japanese Patent Application Publication No. 2013-252853 (JP 2013-252853 A), a difference between running at the time of the CD mode and running at the time of the CS mode is realized by changing the number of opportunities for EV running depending on whether the CD mode or the CS mode is selected. That is, with the aforementioned hybrid vehicle, the number of opportunities for EV running is increased by making the threshold of the power at which the engine starts larger at the time of the CD mode than at the time of the CS mode. Thus, the difference between running at the time of the CD mode and running at the time of the CS mode is realized.
On the other hand, owing to a progress in the technology of power electronics, the performances of a motor, an inverter, the electrical storage device and the like are improved, so the output of the motor can be increased. Due partly to this technical background, the degree of freedom in selecting driving force sources (the engine and the motor) is high in the hybrid vehicle. In the hybrid vehicle having the CD mode and the CS mode, it has been desired to realize special running that makes users feel highly satisfied especially in the CD mode.